Note: Descriptions are shown in the official language in which they were submitted.
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FP065 211381~ '`t, , ,.~,,
Ele~trical Com~onent
This inYention relates to electrical components and to their
5 connection and protection from the environment.
In certain instances, for e2~ample in automotive applications,
where the component will be subject to hostile environments the
component will need to be protected ~rom the environment during use in
~D addition to being connected to the appropriate terminals
According to the present invention, there is provided an elec$rical
component that has a plurality of leads e~tending therefrom, wherein
the component is enclosed in an insulating plastics sleeve, and wherein
~5 the sleeve has a plurality of dimensionally heat-recoverable end portions
that e~tend over the leads and each end portion encloses a quantity of
solder so that each lead can be permanently connected to a conductor by
hea~ing the end portions of the sleeve to cause them to recover and the
solder to fuse.
ao
Although in the broadest aspect of the invention only the end
portions of th~-sleeve need be heat-recoverable in practice it will be most
convènien~ to employ a heat-reco~erable sleeve and recover the central
po~tion thereof into engagement with the component.
Heat-recoverable art~cles are now widely used in many areas
where insulation, sealing and encapsulation are required. Usually
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2113~16
these articles recover, on heàting, towar~s an original shape from
which they have previously been deformed, but the term "heat-
recoverable", as used herein, also includes an article which, on heating,
adopts a new configuration, even if it has not been previously deformed.
In their most common form, such articles comprise a hest-
shrinkable sleeve made from a polymeric material exhibiting the
property of elastic or plastic memory as described, for e~cample, in US
Patents 2,027,962; 3,086,242 and 3,957,372. As is made clear in, for
10 e~ample US Patent 2,027,962, the original dimensionally heat-stable
form may be a transient form in a continuous process in which, for
e~ample, an extruded tube is expanded, whilst hot, to a dimensionally
heat-unstable form but, in other applications, a performed
dimensionally heat staUe article is deformed to a dimensionally heat
~5 unstable form in a separate stage.
Any matenal to which the property of dimensional recoverability
may be imported can, be used to form the heat-recoverable sleeve. For
esample, the sleeve may be formed from a polyolefin, eg. a low, medium
2~) or high density polyethylene, an ethylene copolymer, eg. ethylene vinyl
acetate, a polyamide, eg. nylon 6 or nylon 11 or 12, or a halogen-
containing polymer, especially a Fluoropolymer, eg. polyvinylidene
fluoride, ethylene-tetrafluoroethylene copolymer or
polytetrafluoroethylene. For most applications the preferred polymer for
25 forming the recoverable sleeve will be polyvinylidene fluoride.
Preferably the sleeve includes a quantity of a fusible plastics
material in each end portion that will seal the end portions of the sleeve
iagainst ingress of moisture after recovery of the sleeve. The fusible
30 in~ert may be formed from the same polymer as the sleeve or a different
pobmer may~be employed, normally having a somewhat lower softening
point tha~l that of the sleeve. For esample, in the case of sleeves made
from polyv,inyli-dine fluoride a fusible insert formed from a polyolefin
may be employed.
36
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The component according to the invention ha~ the advantage that
it is relatively easy to install, simply requiring a quantity of heat to form
the electrical connection between the component leads and the terminals
to be connected, and to encapsulate and seal the connections.
The component may, instead, be one that has three or more leads.
For example, a transistor, a multi-contact electrical connector or a
multi-contact switch. However many lead~ the component has, in
certain designs of component the lbads may extend from one side of the
10 component. In this case the sleeve may comprise a plurality of tub~lar
portions each of which extends over one of the leads, and a further sleeve
portion that e~tends over the body of the component, one end of the
tubular portions being retained in the further sleeve portion, for
example by partial recovery of part of the further sleeve portion over the
15 ends of the tubular portions.
The component according to the invention may comp~ise any of a
number of electrical components for e~ample capacitors, resistors,
diodes or two lead circuit protection devices, for example those based on
autotherming carbon loaded polymer~, and normally the component
will be a dual-in-line (D.I.L) component although it is possible for
components in other coIlfigurations to be used.
The invention will now be described by way of e~ample with
25 reference to the accompanying drawing~ in which:
Fi~re 1 is a schematic view of a component according to the
invention;
Fi~re 2 is a schematic view of a component according to the
invention after installation; and
,-~
Figure 3 i9 a view of part of a multi-pin connector according to
the in~ention
Referring to the accompanying drawings an electrical component
which is a resistor has a body 1 and a pair of in-line leads 2 and 3.
.
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WO g3/03510 ~L3~;~ 6 PCr/GBg2/014~
resistor is enclosed in a dimensionally heat-recoverable sleeve 4 formed
from transpsrent poly~rinylidine fluoride that has been crosslinked by
e~posure to high energy electrons and then espanded in its cross-linked
state. The sleeve has a central portion 5 that has been recovered into
5 engagement with the body 1 of the resistor and a pair of end portions 6
and 7 that are in their unrecovered state. Each end portion 6 and 7
contaiDs a ring of pre-~uxed solder 8 and 9 and a ring of uncross-linked
polyolefin 10 and 11. The sleeve 4 extends beyond the ends of the
tenninals 2 and 3.
During installation, a pair of insulated wires comprising
conductors 12 and 13 and insulation 14 and 15 that has been stripped off
the end of the conductors are inserted into the ends of the 61eeve 4 and
the end portions 6 and 7 of the sleeve 4 are recovered about the wires by
~5 being heated by means of a hot-air gun or infrared lamp, during which
the solder 2~ings 8 and 9 fuse to form a solder connection between the
1~ 2 and 3 and the conductors la and 13. DunDg the heating stage the
r~ 10 and 11 fu~e to form a seal against moisture ingress between the
sleeve 4 and the insulation 14 and 1~ a~ shown in Eigure 2.
- Figure 3 shows part of a multi-pin component 31, in this case a
four-tenlunal transistor, e.g. a E$T with a~ pair of gates or a bipoplar
trallsistor with a screen. The component is enclosed in a transparent
heat-recoverable polyvinylidine fluoride sleeve which comprises four
25 ~ hea~reco erable tubular portions 32, one such portion 32 enclosing each
lead 33 of the component, and a further sleeve component 34 of larger
dismete~,~which~ encloses~the body of ~the~component and part of the
tubular portions 32. Each tubu ar portion~32 contains an annular solder
i nu~rt 35 in its central region so that it encircles one of the leads 33 of the30, componenj t.
i on~er to install the component the wires to be connected (which
may, for example, be in~ the ~form ~of separate conductors of a multi-
- conductor cable), are~simply inserted into~the open ends of the tubular
3~ onis 32 and the assembly is~ eently heated by means of a hot-air gun
to fuse the so1der inserts 36 and recOVN the tubular portions 32, thereby
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WO 93!03s10 `~ PCl'tGB92~01408
2~i331S
simultaneously forming insulated solder connections to each of theleads.
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